In recent years, demand for global environmental protection has become increasingly strong. For this reason, in refrigerators, other refrigerating cycle apparatus and the like, it is especially strongly desired to increase efficiency.
Hitherto, in the hermetic compressor utilized in refrigerators, refrigerating cycle apparatus and the like, there has been used a resin suction muffler. These conventional hermetic compressors are disclosed in, for example, Japanese Patent Unexamined Publication No. H05-195953 and the like.
Hereunder, the conventional hermetic compressor is explained with reference to the drawings.
FIG. 9 shows a longitudinal sectional view of the conventional hermetic compressor. FIG. 10 shows a perspective view of a suction muffler used in the conventional hermetic compressor.
In FIG. 9 and FIG. 10, oil 202 is stored in a bottom part of hermetic container 201 (hereafter referred to as “container 201”). Compressing member 204 (hereafter referred to as “member 204”) is supported elastically with respect to container 201 by suspension spring 206.
Member 204 is constituted by motor element 210, and compressing element 220 disposed above motor element 210. Motor element 210 is constituted by stator 212 and rotor 214.
Compressing element 220 has crank shaft 221 (hereafter referred to as “shaft 221”). Shaft 221 is constituted by main shaft 222 and eccentric shaft 224. Main shaft 222 is supported rotatably with respect to bearing 227 provided in block 226. Rotor 214 is fixed to main shaft 222. Additionally, shaft 221 has oil supplying mechanism 225.
Further, piston 228 is inserted so as to be capable of reciprocating with respect to cylinder 230 monolithically formed in block 226. Cylinder 230 forms, together with valve plate 232 (hereafter referred to as “plate 232”), compression chamber 234.
A piston pin (not shown in the drawing) attached to piston 228 is inserted rotatably with respect to coupling part 236 to constitute a coupling means. Eccentric shaft 224 is inserted rotatably with respect to coupling part 236. By this construction, coupling part 236 couples eccentric shaft 224 and piston 228.
Cylinder head 238 covers plate 232. Suction muffler 240 (hereafter referred to as “muffler 240”) is retained by cylinder head 238 and plate 232 while being nipped. Muffler 240 is molded and formed by a resin such as poly-butylene terephthalate. Inside muffler 240, there is provided sound deadening space 242 whose inside face has been formed approximately like a circular cone. In a lower end of muffler 240, there is provided oil discharge opening 246 (hereafter referred to as “opening 246”). In this manner, hermetic compressor 200 (hereafter referred to as “compressor 200”) is constituted.
Next, operation of compressor 200 is explained.
When an electric current is applied to motor element 210, stator 212 generates a rotating magnetic field. By this rotating magnetic field, rotor 214 rotates together with main shaft 222. By the rotation of main shaft 222, eccentric shaft 224 eccentrically moves. An eccentric motion of eccentric shaft 224 is transmitted to piston 228 through coupling part 236. As a result, piston 228 reciprocates in cylinder 230. A refrigerant gas (not shown in the drawing) having returned from a refrigerating cycle (not shown in the drawing) outside container 201 is introduced into compression chamber 234 through muffler 240. The refrigerant gas introduced into compression chamber 234 is compressed in compression chamber 234 by piston 228. The compressed refrigerant gas is sent again to the refrigerating cycle outside container 201.
On the occasion of this refrigerant compression, noise is generated by an intermittent suction of the refrigerant gas. Muffler 240 serves to reduce the generated noise. Additionally, by the fact that muffler 240 is formed by the resin whose heat transfer is small, heating of the refrigerant gas is prevented. By this fact, a decrease in performance of compressor 200 is prevented.
Additionally, by utilizing actions of a centrifugal force generated by the rotation of shaft 221, and the like, oil supplying mechanism 225 supplies oil 202 stored in the bottom part of container 201 to upper compressing element 220. Oil 202 supplied to compressing element 220 lubricates some sliding portions of bearing 227 and the like. Thereafter, oil 202 is dispersed from an upper end of shaft 221 to the environment by the centrifugal force of main shaft 222. Dispersed oil 202 lubricates members such as piston 228 and cylinder 230. Additionally, oil 202 adheres to inside wall surface 250 of container 201, and flows down to the bottom part of container 201 along inside wall surface 250. As oil 202 flows down along inside wall surface 250, heat is conducted from oil 202 to container 201. The heat conducted to container 201 is radiated to the outside of hermetic compressor 200 through a wall surface material of container 201. By this fact, a cooling of compressor 200 is performed.
Further, oil 202 having dispersed from the upper end of shaft 221 is sucked also into muffler 240 with a flow of the refrigerant gas. The flow of the refrigerant gas is released into sound deadening space 242 in muffler 240, and its velocity decreases. When the flow velocity of the refrigerant gas decreases, oil 202 drops to a lower part of sound deadening space 242. Oil 202 having dropped into sound deadening space 242 flows down along inside wall surface 252 of sound deadening space 242. Oil 202 having flowed down collects to a lower end of sound deadening space 242. Thereafter, oil 202 having collected to the lower end of sound deadening space 242 is discharged from opening 246 to the outside of muffler 240.
However, in the above configuration of conventional compressor 200, it is difficult to contrive a miniaturization of muffler 240 with an inside shape of sound deadening space 242 maintained in a shape like the circular cone. This fact hinders the miniaturization of compressor 200.
That is, in order for muffler 240 to achieve a sound deadening function, sound deadening space 242 necessitates a spatial volume (width or depth of sound deadening space 242) larger than a certain value. Further, in order for oil 202 to flow to opening 246 along inside wall surface 252, sound deadening space 242 is shaped like the circular cone having an angle of a certain degree. Thereupon, for muffler 240, a height of a certain degree becomes necessary, so that opening 246 approaches a liquid level of oil 202 stored in the bottom part of container 201.
However, the liquid level of oil 202 stored in the bottom part of container 201 changes by an operating state of compressor 200. Especially, at start-up of compressor 200, a refrigerant gas having dissolved in oil 202 bubbles out due to a pressure drop in container 201. For this reason, the liquid level of oil 202 ascends, so that opening 246 is immersed in oil 202. Additionally, an average pressure in sound deadening space 242 is low in comparison with that in container 201. As a result, a large quantity of oil 202 enters through opening 246 into sound deadening space 242, so that oil 202 is liable to remain in muffler 240.
Further, it is considered to dispose opening 246 while being separated from oil 202 in the bottom part of container 201 by reducing an incline of inner wall surface 252 to thereby suppress a height of muffler 240 to a low level. However, a dropping velocity of oil 202 flowing down along inner wall surface 252 becomes slow, so the oil 202 is not discharged sufficiently from sound deadening space 242. As a result, similarly, oil 202 is liable to remain in muffler 240.
Like this, if the large quantity of oil 202 remains in muffler 240, when the refrigerant gas is sucked into compressing chamber 234, oil 202 is raised, so that the large quantity of oil 202 is sucked into compressing chamber 234.
If the large quantity of oil 202 flows into compressing chamber 234, a load during compressing becomes large. As a result, an input energy of compressor 200 increases. Or, the refrigerant gas is not compressed sufficiently, so that a refrigerating ability of compressor 200 decreases. Further, by the fact that a compressing load and the like abruptly fluctuate, the noise of the compressor 200 becomes larger. Additionally, heat exchanger performance is influenced by the fact that the large quantity of oil 202 is discharged to the refrigerating cycle.